Ahmed Sayyid, 23, said he was waiting in line with friends at an entrance to the Green Zone, hoping for a job interview with Iraqi police, when a woman in a black abaya approached the line.

"Suddenly, she blew herself up about 50 meters from where I was standing," he said.

Guards fired into the air to disperse the crowd after the explosion, he said.

The minibus blast took place in a Shiite Muslim area of eastern Baghdad; police said a bomb had been attached to the vehicle.

There was no evidence that the attacks were linked to a debate over a security pact that would set a timeline for the withdrawal of U.S. troops -- from cities by June 30 and the entire country by Jan. 1, 2012.

But the bombings amounted to a show of defiance and a reminder of the possibility that attacks could increase as American troop levels fall and the Iraqis assume more responsibility.

Under the deal, Iraq would have full responsibility for the Green Zone but would be entitled to request "limited and temporary support" from the U.S. military in maintaining security.

The heavily protected area on the west bank of the Tigris River houses the U.S. Embassy and Iraq's government headquarters.